Railway traffic controlling



Jt me 13, 1939.

H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Feb. 12, 1935 N NAQ mm Q INVENTOR. HOLUQX 7720mps012 ATTORNEY.

Patented June 13, 1939 UNITED STATES PATENT OFFICE RAILWAY TRAFFIC CONTROLLING APPARATUS Application February 12, 1935, Serial No. 6,174

Renewed May 29, 1936 2 Claims.

My invention relates to railway traffic controlling apparatus, and more specifically to apparatus for controlling wayside and/or cab signals by means of coded trackway energy.

One feature of my invention is the elimination, in apparatus of the above character, of all moving parts in the code following elements of the system such as, for example, the contacts of the usual code following track relay or of the locomotive-carried master relay. That is to say, in the system which I provide, decoding in the wayside equipment or aboard the locomotive is accomplished primarily by means of static apparatus, thus eliminating the mechanical and contact Wear to which the usual continuously operating code following apparatus is ordinarily subjected. Other novel features of my invention will become apparent as the description progresses.

The railway trafiic controlling apparatus set forth in my present application is somewhat similar to that set forth in the copending applications of Philip H. Dowling, Serial No. 532,028, filed on April 22, 1931, and Serial No. 219,243, filed on July 14, 1938 (division of SerialNo. 532,028), for Railway signaling systems, and the said copending applications contain claims which cover broadly certain features of the invention described in my present application.

I will describe one form of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view showing a stretch of railway track equipped with apparatus embodying my invention, which apparatus is adapted to be controlled in accordance with the usual frequency type of code. Figs. 1 and 1 are diagrammatic views showing in greater detail certain portions of the apparatus illustrated in Fig. 1.

Similar reference characters refer to similar parts in each of the foregoing figures.

Referring to Fig. 1 of'the drawing, the reference characters"! and I designate the track rails of a stretch of railway track which is divided by insulated joints into a number of blocks of which but two blocks, 23 and 34, are shown. Traffic normally travels over this stretch of track from left to right, in the direction of the arrow. Trainc entering each block is protected by a signal designated by the reference character S with a distinguishing exponent corresponding to the location. The block 23 is intersected by a highway and accordingly, a cut section is provided at the highway location 2 so that traffic passing over the highway may be protected by the high way crossing signals XS.

At the leaving end of each track section is a track transformer T1 which supplies coded alternating current to its associated section when 5' trafilc conditions in advance of the section are favorable. In the apparatus which is shown, but two codes are used, these being sufficient for the relatively simple form of two-block three-indication system illustrated. One of these codes is furnished by a constantly operating coding device or code transmitter CT-'!5 and, in the present embodiment, consists of alternating current which is periodically interrupted or varied at a constant rate, such for example, as 75 times per minute. This code is used to provide a caution or Y indication in the apparatus of Fig. 1. The proceed or G indication code is furnished by a similar constantly operating code transmitter CT-JBQ and consists of alternating current which is periodically interrupted at a difierent rate such as 180 times per minute. The code transmitters CT-l5 and CT-l80 are constantly supplied with current from a direct current source having the terminals B-C. It is obvious that these transmitters may be operated from an alternating current source if desired, and that instead of being constantly operated, they may be energized in any suitable manner at such times only as required by trafiic conditions in the asso- 3o ciated track sections. The selection of the code which is furnished to the track transformers 'IT is determined by trafiic conditions in advance in a manner which will be clear from the description which follows.

Each track section is provided with what may be conveniently termed a track relay of the saturation type, designated by the reference charactcr TR. and designed in such a manner that the presence of a relatively small amount of direct current in a saturating or control winding of the relay causes a relatively large change in impedance of the main relay windings. In its essential elements this relay comprises a saturable core on whi h are wound a saturation or input winding and an impedance or output winding. A relay of this type is described in the United States Patent No. 1,936,705, granted to H. D. Abcrnethy, for Automatic railway block signaling system.

Referring for the moment to Fig. 1 the track relay TR preferably comprises a three-legged magnetizable core on the central leg of which is mounted a control or saturation winding 5, and on the two outer legs of which are mounted the main or impedance windings 6 and 1. The windings 6 and I are wound in such a direction as to set up opposing fluxes in the middle leg of the core, thereby preventing alternating current from being induced in the control winding 5. For some purposes, as will be explained hereinafter, additional impedance windings 24 and 25 may be used. The saturation relay AR illustrated in Fig. 1 is similar to the track relay TR of Fig. 1 but dispenses with the additional windings 24 and 25.

Associated with each track relay of the apparatus shown in Fig. 1 is a relay transformer RT which insulates the winding 5 from the track rails, and a rectifier K which converts the coded alternating current received from the rails into pulses of unidirectional current in winding 5. Considering location 2, windings 6 and I of the track relay TR. are connected with an alternating current source having the terminals BX-CX, through the primary winding 8 of an auxiliary transformer AT During the on period of the code, the rectified current in Winding 5 saturates the core of relay TR. and allows alternating current to flow in the primary winding 8 of transformer AT During the ofi period of the code, the control winding 5 receives no energy so that the windings 5 and I of relay TR represent a high impedance in series with winding 8 of transformer AT with the result that this transformer receives practically no energy during the ,oif code period. It will be apparent from the foregoing, therefore, that transformer AT will receive impulses of energy in step with the code being supplied to the track section 2-3.

The output of transformer AT is rectified by the rectifier L and is impressed across a portion of the winding of the decoding transformer DT This decoding transformer furnishes energy to an untuned direct current relay H which relay is energized through the secondary winding 9 of transformer U1 and a rectifier M Relay H is so designed that it will remain energized whenever transformer DT is receiving impulses either of '75 or 180 code. The direct current decoding relay J receives energy from a portion of the winding of transformer DT and is connected through a decoding unit "DU of well-known type. The details of unit DU are not shown but this unit usually comprises a rectifier and a reactor-condenser tuning unit for tuning relay J whereby it will become energized on impulses of 180 code supplied to transformer DT but will remain deenergized when the impulses received are of 7,5 code.

When relay H is energized, direct current is supplied from the source having terminals BC over. the coding contact H of transmitter CT-l80 and the front contact l4-|5 of relay H to the control winding ID of the auxiliary saturation relay AR at location 2. If relay H is deenergized, direct current will be fed to winding ID of relay AR over the coding contact I! of transmitter CTT5, and back contact I 4--l6 of relay H The impedance windings H and I2 of saturation relay AR are in series with the primary winding of transformer IT and also in series with the alternating current source BXCX, so that transformer 1T will receive code impulses in step with the impulses which are delivered to saturation winding Hi. Therefore, when winding 5 of relay TB is receiving either I86 or 15 code, relay I-I will be energized and consequently I80 code will be supplied to the rails of the section in the rear of location 2. Similarly, when winding 5 is not receiving code so that relay H is deenergized, 15 code will be supplied, in like manner; to the rails of the roar section.

Referring now to the cut section location 2 the track relay TR, is provided with additional windings 24 and 25 for the purpose of controlling a clearing-out relay F which controls the operation of the protective apparatus at the highway crossing. Relay F is controlled through a transformer T and a rectifier N and is designed to remain energized whenever winding 5 of relay TR. is receiving code. The track relay TR serves to repeat the code which it receives, to the section in the rear, so that whatever code is supplied to section 2 3, this same code will be repeated into the rear section 22 Having described the various elements of the system individually, I shall now explain the operation of the system as a whole. In doing this, I shall assume that a train enters the section 2-4 from the left, the remaining sections in advance being unoccupied. Just prior to the entry of the train, sections 23 and 34 will both be receiving H30 code and the respective relays H and J at locations 2 and 3 will all be energized so that the signals S will indicate proceed. The circuit for the G lamp of signal S includes front contact iii-22 of relay H and front contact lB-Ziiof relay J Similar circuits will be effective for energizing signals 8 and S As soon as the train enters section 22* energy will be cut off from winding 5 of relay TR. so that trans formers AT and DT will become effectively deenergized and will cause both decoding relays H and J to release. Signal S will now indicate R over the back contact l823 of relay H At the same time, due to the entry of the train into section 2-4 relay F will become deenergized and will open its front contact 26 to deenergize the left-hand winding of the highway crossing relay m. In this manner, operation of the crossing signals XS will be initiated with the entry of the train into the section.

When the train progresses beyond location 2 winding 5 of relay TR will be deprived of current so that the clearing-out relay F will be deenergized and will close its back contact 21, opening its front contact 28. The closing of back contact 21 causes steady or uncoded alternating current energy to be supplied to track transform or TT for the purpose of causing energization of relay F As soon as the train has completely vacated section 2-2 sufficient energy will be received by relay F due to the lowered impedance of windings 24 and 25 of relay TR. to cause front contact 25 to close, thereby energizing the lefthand winding of relay XR to restore the signals XS to the inoperative condition.

Nothing further happens until the train enters section 34. When this occurs, relays H and J will both release and section 23 will be supplied with current of 15 code over a circuit which will be clear from the description previously given. As soon as the train completely vacates section 2 3, track relay TR will respond to the 75 code current in its saturation winding 5 and relay P will become energized, thus opening back contact 2'! to remove steady energy from the section 2-2 The 15 code Will be repeated from section 2 3 into the rear section 2-2 and will cause relay H to become energized. Signal S will now indicate Y, over the front contact Iii-22 of relay H and the back contact l9-2I of relay J Under this condition, I80 code will be supplied to the section in the rear of section 22=*.

When the train vacates section 3-4, current of 15 code will be supplied to this section to energize relay H whereby current of 180 code will be supplied to the two track circuits of section 2-3. Signal S will now indicate G. When the train completely vacates the section in advance of location 4, section 3-4 will also receive I80 code, so that signal S will indicate G and all the apparatus of Fig. 1 will be restored to the condition in which it is illustrated.

The purpose served by front contact 28 of relay F is to provide for initiating the operation of the crossing signals XS as soon as a train traveling in a direction opposed to that indicated by the arrow passes location 3. This is accomplished by the deenergization of the righthand winding of the crossing relay XR, which relay will set the crossing signals into operation by means of circuits which are well known and V which it is unnecessary to describe in detail.

It will be understood that relays l3 and F may be of the alternating current type, in which case the respective transformers "l? and T and rectifiers N and N may be eliminated. The use of direct current relays which are energized from rectifiers has the advantage that slow acting characteristics are more readily obtainable with this combination than if alternating current relays are used.

The system disclosed is also applicable to direct current track circuits, in which case the transformers RT and rectifiers K may be eliminated, the control winding 5 of the track relays TR being connected directly with the track rails.

It will be clear that the system disclosed is not limited to track circuits of the coded rail current type, as a two-indication system may be provided by using steady or uncoded current in the rails. In such case, relays H may be energized directly from the rectifiers L, eliminating the decoding transformers DT and rectiflers M. Furthermore,

'11 coded track circuits are used, any suitable type of code such, for example, as the time or "pattern code, or the count code may be used, the system being not limited to the frequency type of code which has been used for purposes of illustration only.

Although the system disclosed shows the control of wayside equipment only, it will be readily apparent that the apparatus can also be used to control locomotive cab signaling equipment. In such case, the control winding of the saturation relay on the locomotive will receive its saturation energy inductively from the rails by means of receiving equipment which is well-known in the art, and the saturation relay will be used to control cab signals in a manner similar to that disclosed in connection with the control of the wayside signals S in Fig. 1.

Although I have shown and described but one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a first and a second section of railway track, means for supplying coded current to the rails of said first section, a saturation relay comprising a magnetizable core having an input winding receiving coded energy from the rails of said first section for changing the flux in said core in step with said coded energy and having a first and a second output winding on said core, means including said first output winding for at times supplying coded current to the rails of said second section, a normally energized relay receiving energy at said times from said second output winding, and means efiective when said last mentioned relay is deenergized for supplying uncoded current to the rails of said second section.

2. Decoding means for coded A. 0. track circuits comprising a rectifier receiving energy from the track rails of a given section, a transformer, a decoder including relays selectively responsive to the periodicity of energization of said transformer, a local source of current for energizing said transformer, means including a voltage responsive device all of the component parts of which are stationary, said device being responsive to a diiference of potential supplied by said rectifier, for controlling the energization of said transformer from said local source, and means controlled by one of said decoding relays and including a saturable device all of the component parts of which are also stationary for supplying current to the track rails in the rear of said given section.

HOWARD A. THOMPSON. 

